Although the existence of circulating tumor cells (CTCs) has been
known for well over a century, actually finding them in the bloodstream
for further investigation has been virtually impossible. Until now.
Using a microchip, investigators from the Massachusetts General
Hospital BioMicroElectroMechanical Systems (BioMEMS) Resource Center
and the MGH
Cancer Center are now able to isolate these CTCs from a simple
blood sample. The ability to do this could potentially change how
doctors manage cancer care. Imagine using a blood test to manage
how a tumor is responding to treatment or better yet, as a tool
for early detection.
"We looked at four major cancer killers and
were able to consistently find these cells and correlate test results
with traditional monitoring techniques, "says Mehmet Toner,
PhD, senior author of the report in the December 20 issue of Nature
and director of the MGH BioMEMS Resource Center.
The microchip-based technique involves using a business-card-sized
silicon chip, called the CTC-chip, covered with almost 80,000 microscopic
posts coated with a glue-like antibody to a protein expressed on
most solid tumors. The blood flows through the chip allowing the
CTCs to stick to the posts. Since they are so rare, the key to detecting
CTCs is to sample a sufficient amount of blood --other devices have
not been able to accomplish this. With the CTC-chip, MGH researchers
have been able to test samples that are 1,000 to 10,000 times larger
than previous technology has allowed. Once captured, they were able
to analyze the levels of CTCs in the bloodstream and determine changes
in tumor size in response to treatment.
"While much work remains to be done, this approach
raises the possibility of rapidly and noninvasively monitoring tumor
response to treatment, allowing changes if the treatment is not
effective," says Daniel Haber, MD, director of the MGH Cancer
Center and a co-author of the Nature report.
